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Plecoglossus altivelis:   (click for more)

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  • Salmo (Plecoglossus) altivelis  Temminck & Schlegel, 1846: 229 (original description).
  • Plecoglossus altivelis ryukyuensis  Nishida, 1988: 236.
    FAO Names
    En - Ayu sweetfish, Fr - Ayu, Sp - Ayu.
    3Alpha Code: PCA     Taxonomic Code: 1230301601
    Diagnostic Features
    Body elongate.  Scales small and cycloid; lateral line complete with 145-169 scales.  Mouth large; teeth on both jaws small and conical in juveniles; movable, broad, lamelliform (placoids) and 11 to 14 in number on each side in adults.  First arch branchial with 46-49 gillrakers.  Dorsal fin high, with 10-11 rays; adipose fin present. Anal fin with 14-15 rays. Pectoral with 14. Pelvic fin base below middle of dorsal fin.  Vertebrae 59-63. 
    Geographical Distribution

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    Western Pacific Ocean; from western Hokkaido southward in Japan, the Korean Pen., Taiwan, and China.
    Habitat and Biology
    Typical amphidromous.
    Adults spawn in the spring, in the lower reaches of rivers. After spawning, some adults die while others return to the sea.  Larvae enter the sea immediately after hatching and remain there during winter, feeding on plankton.In springtime, the young (5-7 cm) move upstream to the middle reaches of rivers to feed on algae.
    Those that are ready to spawn (about 20 cm of total length) move downstream to the lower reaches as well. Some fish spawn two or three years in succession, others only once. 
    To about 30 cm; usually 20 cm.
    Interest to Fisheries
    Most important species in Japanese freshwater fisheries, highly esteemed as food and game fish. Propagated commercially everywhere in western Japan. The total catch reported for this species to FAO for 1999 was 11 380 t. The countries with the largest catches were Japan (11 380 t).
    Marketed fresh and consumed fresh, fried and broiled.
    Local Names
    English : Ayu ,  Ayu sweetfish ,  Koayu ,  Sweetfish .
    Finnish : Aju .
    French : Ayu .
    Japanese : Ayu ,  Koayu .
    Sex easily distinguished by the shape of anal fin. Number of fin rays, scales and vertebrae tends to increase in northern populations.
    Araga, C. - 1984 Plecoglossidae. In: H. Masuda; K. Amaoka; C. Araga; T. Uyeno; T. Yoshino (eds.). The Fishes of the Japanese Archipelago. Tokai. Univ. Press. 33-34.
    Azuma, M. - 1977Specific problems on the "Ayu" fish of Lake Biwa. The Freshwater Fishes, (3): 78-85.
    Froese, R. and D. Pauly. Editors. 2003. FishBase. World Wide Web electronic publication. www.fishbase.org
    Vera, J. - 1992Diccionario multilingüe de especies marinas para el mundo hispano. Ministerio de Agricultura, Pesca y Alimentación. Secretaria General Técnica. 1282 pp.
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